Competition Tire Wear Question
05-15-2002, 12:00 AM
#1
Race Car
Thread Starter
Competition Tire Wear Question
Adrial and I aren't sure about the following:
I inflate my tires for autocross so that I don't scuff any part of the sidewall. Should I be wearing the shoulder of the tire [highlighted in green above] or should I only be using the actual tread area of the tire and inflate my tires a bit more so I'm not wearing the shoulder? Thanks.
I inflate my tires for autocross so that I don't scuff any part of the sidewall. Should I be wearing the shoulder of the tire [highlighted in green above] or should I only be using the actual tread area of the tire and inflate my tires a bit more so I'm not wearing the shoulder? Thanks.
05-15-2002, 12:07 AM
#2
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hey i have those tires for my r/c car... looks nice... i inflate my tires to 5 psi above what Porsche says they should be regularly 29F/36R, i have 34F/41R and a bit of wear on the shoulder tread where the tread curves to the shoulder for about 1/2 in, but not on the sidewall... i have fulda carat extremos.
05-15-2002, 12:23 AM
#3
You should be using about 1/2 that area. I like tire pressures of about 4-6 more in front than rear (for 944/S) Others suggest at least even pressures F/R for track/ AutoX.
05-15-2002, 12:27 AM
#4
Race Car
I don't think there is a set answer that covers all brands, models and sizes. What works best for one tire, may not be best for another. I believe the goal is to keep as much tread in contact with the ground as posible. When inflated to the point where sidewall flex is minimized, many tires are starting to bulge in the center, and the tread near the shoulder starts to lift, leaving less contact area. A pyrometer can measure temps across the tread, cool spots aer doing less work, hot spots more work, even temp all the way across is ideal. Shoe polish will tell you very little in the long run, I stopped using it at my 3rd autocross. I hope that ramble makes sense.
05-15-2002, 12:33 AM
#5
Nordschleife Master
So dave, wanna invest in a pyrometer...?
Split it between all the NNJR Rennlist people that are interested...
How much do they run for? $200?
Btw yes the ramble made sense, somewhat.
Oh yea, I learned something playing GT3...
You go faster if you start turning before you actually get to the turn...so that by the time you round the cone you're already lining up for the next one. correct?
Split it between all the NNJR Rennlist people that are interested...
How much do they run for? $200?
Btw yes the ramble made sense, somewhat.
Oh yea, I learned something playing GT3...
You go faster if you start turning before you actually get to the turn...so that by the time you round the cone you're already lining up for the next one. correct?
05-15-2002, 12:35 AM
#6
Race Car
Thread Starter
Well my A032's have some decent sidewalls, so they don't flex much under hard cornering. I'm currently running 34-36 PSI on all four and I'm about a 1/4 inch away from scrubbing the sidewalls...the wear is well into the shoulder area. Sounds like I'm running the right pressure for my tire based on what you're saying.
Little Ariel, however, is running BFG G-Force TA KDW's...they have very stiff sidewalls [perhaps even stiffer than my Yokohamas have] but is there a difference under cornering where he should have his pressure set? If he's not getting much flex can he run something lower like I'm doing?
Little Ariel, however, is running BFG G-Force TA KDW's...they have very stiff sidewalls [perhaps even stiffer than my Yokohamas have] but is there a difference under cornering where he should have his pressure set? If he's not getting much flex can he run something lower like I'm doing?
05-15-2002, 12:39 AM
#7
Nordschleife Master
[quote]Originally posted by PorscheG96:
<strong>
Little Ariel, however, is running BFG G-Force TA KDW's...they have very stiff sidewalls [perhaps even stiffer than my Yokohamas have] but is there a difference under cornering where he should have his pressure set? If he's not getting much flex can he run something lower like I'm doing?</strong><hr></blockquote>
Yah, what Porsche Gay 96 said..
<strong>
Little Ariel, however, is running BFG G-Force TA KDW's...they have very stiff sidewalls [perhaps even stiffer than my Yokohamas have] but is there a difference under cornering where he should have his pressure set? If he's not getting much flex can he run something lower like I'm doing?</strong><hr></blockquote>
Yah, what Porsche Gay 96 said..
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05-15-2002, 01:02 AM
#8
Race Car
[quote]Originally posted by adrial:
<strong>So dave, wanna invest in a pyrometer...?
Split it between all the NNJR Rennlist people that are interested...
How much do they run for? $200?
Btw yes the ramble made sense, somewhat.
Oh yea, I learned something playing GT3...
You go faster if you start turning before you actually get to the turn...so that by the time you round the cone you're already lining up for the next one. correct?</strong><hr></blockquote>
A)I'm working on it, well, working on how to get it past my wife. prices have come down a bit recently,I think I saw one for around $130.
B) If you mean setting up your exit from a turn as you go into the turn, YES. If you mean compensating for drift, STAY AWAY FROM ME!!! Oh wait, I haven't seen you drift yet, try pushin' it a little harder
C) I have ZERO experience with your BFGs.
<strong>So dave, wanna invest in a pyrometer...?
Split it between all the NNJR Rennlist people that are interested...
How much do they run for? $200?
Btw yes the ramble made sense, somewhat.
Oh yea, I learned something playing GT3...
You go faster if you start turning before you actually get to the turn...so that by the time you round the cone you're already lining up for the next one. correct?</strong><hr></blockquote>
A)I'm working on it, well, working on how to get it past my wife. prices have come down a bit recently,I think I saw one for around $130.
B) If you mean setting up your exit from a turn as you go into the turn, YES. If you mean compensating for drift, STAY AWAY FROM ME!!! Oh wait, I haven't seen you drift yet, try pushin' it a little harder
C) I have ZERO experience with your BFGs.
05-15-2002, 04:50 AM
#11
Race Director
"I'm currently running 34-36 PSI on all four and I'm about a 1/4 inch away from scrubbing the sidewalls...the wear is well into the shoulder area. Sounds like I'm running the right pressure for my tire based on what you're saying."
Hmmm, I'm using those same tires on my 951 and I'm getting ZERO wear on the sidewalls... Yeah sounds like pressure is ok. Pressure should only be used to adjust temperature balance between tire center vs. edges, not for outside vs. inside edge wear (or rollover). You want to set pressure such that the center temperature is the same as the average of the inner and outer edges. The fallacy of using chalk on the corner of the tire is hopelessly simplistic and naive. That's because by the time you increase pressure such that you have no outside edge wear & rollover, your inside edge is completely off the ground and your tires' centers are taking ALL of the load.
No, the real issue here is not enough negative camber. You want to start with something in around -2.5 to -3.0 degrees for road-racing and -3.0 to -3.5 for autocrossing (about 0.5 degree less in rear).
Then using a pyrometer, measure outside edge, center and inner edge temperatures and adjust as follows:
1. if center temp is less than average of outside & inner edges, then increase pressure.
2. if center temp is more than average of outside & inner edges, decrease pressure.
4. if outer edge temp is more than inner edge, increase negative camber.
5. if outer edge temp is less than inner edge, decrease negative camber.
That's it! Pretty simple and after you check all four steps and adjust accordingly, you'll have the most even tire temps and wear with maximum grip possible. And this requires meticulous records in a logbook since alignment specs will be different for different tracks, driving styles, and tire brands & models.
Good deal on pyrometer here: <a href="http://www.racerpartswholesale.com/long12.htm" target="_blank">http://www.racerpartswholesale.com/long12.htm</a>
Hmmm, I'm using those same tires on my 951 and I'm getting ZERO wear on the sidewalls... Yeah sounds like pressure is ok. Pressure should only be used to adjust temperature balance between tire center vs. edges, not for outside vs. inside edge wear (or rollover). You want to set pressure such that the center temperature is the same as the average of the inner and outer edges. The fallacy of using chalk on the corner of the tire is hopelessly simplistic and naive. That's because by the time you increase pressure such that you have no outside edge wear & rollover, your inside edge is completely off the ground and your tires' centers are taking ALL of the load.
No, the real issue here is not enough negative camber. You want to start with something in around -2.5 to -3.0 degrees for road-racing and -3.0 to -3.5 for autocrossing (about 0.5 degree less in rear).
Then using a pyrometer, measure outside edge, center and inner edge temperatures and adjust as follows:
1. if center temp is less than average of outside & inner edges, then increase pressure.
2. if center temp is more than average of outside & inner edges, decrease pressure.
4. if outer edge temp is more than inner edge, increase negative camber.
5. if outer edge temp is less than inner edge, decrease negative camber.
That's it! Pretty simple and after you check all four steps and adjust accordingly, you'll have the most even tire temps and wear with maximum grip possible. And this requires meticulous records in a logbook since alignment specs will be different for different tracks, driving styles, and tire brands & models.
Good deal on pyrometer here: <a href="http://www.racerpartswholesale.com/long12.htm" target="_blank">http://www.racerpartswholesale.com/long12.htm</a>
05-15-2002, 09:11 AM
#12
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O32 R's have a little arrow on the sidewall, and they are designed to roll over so that the scuff marks on the sidewall extend to the little arrow. Take a look at the tire. I run around 30 front and 28 rear cold, and 40 hot all around. Your wheel width, tire size and camber will all come into play.
05-15-2002, 10:46 AM
#13
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All this talk regarding the 032 tires is great!
I was thinking of getting them for my other set of rims (16" x 8 & 9)...
Those of you using them, do you street the tires at all other than to-from the auto X or DE? I would kind of like to "sport" my wheels when i get them re-finished...
I was thinking of getting them for my other set of rims (16" x 8 & 9)...
Those of you using them, do you street the tires at all other than to-from the auto X or DE? I would kind of like to "sport" my wheels when i get them re-finished...
05-15-2002, 02:55 PM
#14
Race Car
Thread Starter
[quote]Originally posted by PSUice944:
<strong>All this talk regarding the 032 tires is great!
I was thinking of getting them for my other set of rims (16" x 8 & 9)...
Those of you using them, do you street the tires at all other than to-from the auto X or DE? I would kind of like to "sport" my wheels when i get them re-finished...</strong><hr></blockquote>
I've put about 2k miles and 5 autocrosses on my 32's and they've lost about 2/32nds of tread [They begin with 6/32nds]. After a few heat cycles my guess is they'll harden up and begin to last a VERY long time, though not perform as well in competition. They are LOUD, they TRACK, and are ROUGH on the street, I love them they are RAW tires, and there isn't a better rain tire on the market!
<strong>All this talk regarding the 032 tires is great!
I was thinking of getting them for my other set of rims (16" x 8 & 9)...
Those of you using them, do you street the tires at all other than to-from the auto X or DE? I would kind of like to "sport" my wheels when i get them re-finished...</strong><hr></blockquote>
I've put about 2k miles and 5 autocrosses on my 32's and they've lost about 2/32nds of tread [They begin with 6/32nds]. After a few heat cycles my guess is they'll harden up and begin to last a VERY long time, though not perform as well in competition. They are LOUD, they TRACK, and are ROUGH on the street, I love them they are RAW tires, and there isn't a better rain tire on the market!
